The present disclosure relates to an electrostatic latent image developing toner.
In electrophotography, an electrostatic latent image is typically formed on the surface of a photosensitive drum by exposing the surface of the photosensitive drum to light while in a charged state. The electrostatic latent image is subsequently developed using a toner to form a toner image on the surface of the photosensitive drum. The toner image is subsequently transferred onto a recording medium, thereby forming an image on the recording medium.
An electrostatic latent image developing toner includes a plurality of toner particles. The toner particles are prepared through a mixing process of mixing components such as a binder resin, a colorant, a charge control agent, a releasing agent, and a magnetic powder, a kneading process of kneading the resultant mixture, a pulverizing process of pulverizing the resultant kneaded mixture, and a classifying process of classifying the resultant pulverized product.
The electrostatic latent image developing toner develops an electrostatic latent image on a photosensitive member through electrostatic force resulting from triboelectric charging of the toner. In general, excessive charging of the toner tends to occur when printing is performed successively on a large number of sheets, leading to reduced image density.
An external additive may be caused to adhere to the surface of the toner particles in order to improve properties of the toner in terms of fluidity, charging stability, and ease of cleaning residual toner that has not been transferred from the photosensitive member. Examples of substances that can be used as the external additive include particles of inorganic materials such as silica and titanium oxide.
Particles of inorganic materials, such as silica, that can be used as the external additive tend to include silanol groups and as a consequence tend to be hydrophilic and negatively chargeable. Therefore, when particles of an inorganic material such as described above are to be used as the external additive, the surface of the external additive particles is treated using a surface treatment agent in order to make the surface of the toner particles positively chargeable. Examples of surface treatment agents that can be used include silane coupling agents and silicone oil.